Artifacts Deceive: The Electroretinogram in the Electroencephalogram of a teenager with cerebral anoxia

Artifacts on an electroencephalogram (EEG) - whether physiologic or non-physiologic - can be common and are important to recognize to prevent errors in interpretation. One such EEG artifact is an electroretinogram (ERG) artifact which occurs during photic stimulation. Typically, of a low amplitude, its presence is usually obscured by normal EEG activity over the frontopolar channels but it can appear prominent in very suppressed or EEG recordings showing electrocerebral inactivity. Overall, rarely reported in the literature, the purpose of this case report is to highlight the presence of an ERG artifact in a teenage boy where EEG was obtained after a cerebral anoxic event. It is important that EEG readers identify this to be a non-cerebral waveform in order to provide an accurate assessment of neurologic prognosis.